With recent developments in weapons technology combined with an evolving face of global terrorism, there has been an increase in the threat posed to aircraft in combat, rescue and humanitarian missions. In particular, terrorist militiamen are using inexpensive, portable and readily available weapons such as sniper rifles, assault rifles and shoulder-fired missiles against low flying aircraft, such as helicopters and airplanes, during flight, landing and takeoff. Many military aircraft have systems on board to identify approaching surface-to-air or air-to-air missiles and can defend themselves by deploying appropriate countermeasures.
However, sniper rifles and assault rifles pose larger problems to civilian aircraft as well as conventional on-board defense systems on military aircraft. These weapons tend to be lightweight and require little or no training to operate. Moreover, the projectiles from these weapons are much smaller than conventional missiles. Consequently, they are difficult to detect using conventional on-board missile defense systems. Additionally, these weapons are difficult to counter because they are portable. There could be any number of armed individuals moving from one place to another firing at overhead aircraft. Therefore, target aircraft would need to not only deploy counter measures, but also identify and neutralize the source of the gunfire.
Few systems exist for determining the location of a shooter from an aircraft. These systems generally include sensors that record acoustic shockwave-only signals generated by the projectile. One such airborne shooter detection system is disclosed in commonly-owned U.S. patent application Ser. No. 12/220,745, the contents of which are incorporated herein in their entirety. However, when multiple projectiles are fired at an aircraft and/or when these projectiles are fired by multiple shooters, these systems may have difficulty determining the location of the shooter(s). Airborne shooter detection systems may incorporate infra red (IR) or ultra violet (UV) sensors to detect incoming projectile tracer fire, but these systems have a significant disadvantage in that they are unable to detect ball ammunition.
Accordingly, there is a need for an airborne shooter detection system that is capable of determining the location(s) of one or more shooters who fire multiple projectiles at an aircraft.